Canker sores are recurrent, painful superficial oral ulcers that persist for several days to two weeks or more. Canker sores generally affect about 30% of the population. The lesions associated with canker sores are known technically as recurrent aphthous stomotitis (RAS) or aphthous ulcers. RAS may be "minor" or of a more serious "major" variant.
In general, canker sores or aphthous ulcers are characterized by small white spots associated with small ulcerations on the mucous membrane of the mouth. Up until recently, it was believed that these ulcerations were caused by a herpes virus or fungus, or after enteric use of broad spectrum antibiotics. Canker sores are one of the most common soft tissue diseases seen by the dentist. Canker sores may occur in any area of the oral cavity, in small groups or singularly.
Although there has been a great deal of research on the problem of canker sores, the cause and cure of these lesions remains obscure. Many mechanisms have been proposed including physic, allergic, microbial, diet, traumatic (stress), endocrine, hereditary and auto-immune.
Canker sores may affect patients of any age, but generally, those individuals between the ages of twenty and fifty years and especially women, are prone to outbreaks. In general, canker sores occur in women about twice as frequently as they occur in men. The frequency and severity of outbreaks vary remarkably between patients and within the same patient. In certain individuals, outbreaks occur once or twice a year, while in others, outbreaks may occur once or twice a month.
The outbreak of canker sore lesions is generally preceded by a prodromal period of several days during which period the patient experiences a burning or itching sensation in the oral mucosal area. The onset may also be preceded by a low grade fever and/or lymph node irritation. Upon onset, well defined ulcers form of approximately two to ten millimeters in diameter. These ulcers are generally surrounded by an intense erythematous halo with the base of the ulcer covered by a grayish necrotic tissue. Large, long standing ulcers are called major aphthae and involve the mucous glands, muscle and connective tissue. At this level, the disease may be quite painful and heal with scarring. In certain individuals, the ulcers never really disappear, with a new ulcer appearing as the older one heals.
Although there is a pyschosomatic component to the disease, and prominent feature is acute inflammation, a bacteria has also been isolated as a possible contributor to the disease process. This organism, Streptococcus sanguis, is found in the normal flora of the mouth. It is quite possible, that the above-described mechanisms which are associated with the disease may predispose an individual to bacterial infection by Streptococcus sanguis. There appears to be an immune response against this organism as well as to the epithelial tissue it infects. The ensuing inflammatory response causes localized damage to the host in the form of degeneration and necrosis.
In the acute form, several treatments are presently available including: tetracycline mouth rinses, topical cortisone and anesthetic mouth rinses. Systemic analgesics also may be administered. However, all of these therapies are fairly extreme and are generally reserved for multiple ulcers or major aphthae. All of these therapies should be carefully monitored.
Lactic acid, also known as 2-hydroxypropanoic acid, is a three carbon organic acid found in nature and the human body, is generally produced during the metabolism of sugars by lactic acid bacteria. Lactic acid may be found in sour milk, in molasses, in apples and other fruits, tomato juice, beer, wine, opium, ergot, foxglove and several higher plants. Lactic acid is generally prepared commercially by "lactic acid fermentation" of carbohydrates such as glucose, sucrose and lactose by Bacillus acidi lacti or related organisms such as Lactobacillus delbrueckii and Lactobacillus bulgarius, among others.
Therapeutically, lactic acid has been used as an acidulant, and in veterinary medicine, as a caustic, in dilute solutions to irrigate tissues and as an antiferment. Lactic acid is not known for its analgesic, anti-allergic or anti-microbial activity.